Fabrication of polyaniline/titanium dioxide composite nanofibers for gas sensing application

Polyaniline/titanium dioxide (PANI/TiO2) composite nanofibers were prepared by combining the electrospinning technique with chemical oxidation polymerization. Firstly, Mn3O4/TiO2 nanofibers were prepared by electrospinning, and then the Mn3O4 in the Mn3O4/TiO2 nanofibers acted as an oxidant to oxidatively polymerize aniline. As a result, Mn3O4 was completely consumed while PANI/TiO2 composite nanofibers were formed. The gas sensors of the composite nanofibers with different PANI to TiO2 ratios were fabricated on home-made gold electrodes, and the sensing property for ammonia gas detection was investigated at room temperature. Results showed that the composite nanofiber sensor could detect as low as 25 ppb ammonia gas, which is superior to the PANI nanofiber without TiO2 nanoparticles. The sensing sensitivity of the composite nanofibers strongly depends on the ratio of PANI to TiO2. The mechanism of sensitivity enhancement of the PANI nanofiber sensors mixed with TiO2 nanoparticles was also discussed.

► A simple method for preparation of polyaniline/TiO2 composite nanofibers using electrospun nanofibers of Mn3O4/TiO2 as the templates was reported in this study.
► The p–n junction between polyaniline and TiO2 surface could significantly enhance the sensitivity of the ammonia sensing.
► The sensor made from these composite nanofibers can detect 25 ppb ammonia in gas, which is much higher than that of pure polyaniline nanofibers.